Yes I'm very confused about this too.

I have also seen a non-Tidal CNJ/WHM shield drop today, AFTER the patch.
I even have this recorded on my PS4.

I already had a non-Tidal CNJ/WHM shield before the patch, and the shield was NOT upgraded to Tidal.

I don't understand any of this, I also hope this is a bug.

But seeing the RNG fetish route this game has taken, I wouldn't be surprised if they just come and say it's " working as intended "